Laser donor element

#This invention relates to use of a laser donor element and process for producing a laser-induced white transfer image.

#There is great interest in the generation of images using thermal transfer technology, particularly in the generation of images via near-infrared laser devices. In general, most of these systems rely on the conversion of light to heat energy by an IR absorber, and the subsequent transfer of colorant or other imaging material from the exposed areas to a receiver. The images derived may be monochrome, or by repetition of the process with various colored donors, a multi-colored image can be produced on a common receiver, useful for generating color proofs. The process can also be used to transfer other materials to a receiver, such as IR absorbing materials, UV absorbing materials, polymeric binders or other useful imaging materials. This process is described, for example, in U.S. Pat. No. 5,126,760 which discloses the use of an IR absorber to effect sublimation or diffusion of a colorant from a donor element to a receiver layer.

#U.S. Pat. No. 5,278,023 discloses a propellant-containing thermal transfer donor element which is used to mass transfer colorants to a receiver element. However, there is a problem with this element in that during laser imaging, a portion of the infrared-absorbing material transfers to the receiving element and causes color contamination.

#Comparison 1

#A propellant layer coating composition was prepared consisting of 6.16 g of a 10% solution of vinyl polymer 14 described above in cyclopentanone:N-methyl-2-pyrrolidinone (NMP) (2:1 wt. ratio), 2.05 g of a 5 wt. % of cyanine dye 5 illustrated above in NMP:methanol (2:1 wt. ratio) and 11.78 g cyclopentanone and NMP (2.5:1 wt. ratio). This composition was coated on a 100 μm polyester support which had been previously coated with a 0.43 g/m2 gelatin layer.

#After drying, a colorant transfer layer was then coated on top of the propellant layer consisting of a mixture consisting of 4.72 g of a 40 wt. % dispersion of TiO2 in toluene, 1.05 g of resin, Staybelite® Ester 10 (Hercules Incorporated), 0.15 g of polycaprolactone, Tone® 767 (Union Carbide Corporation), and 14.08 g of toluene using a wire rod coater to provide a colorant layer with a dry laydown of 2.81 g/m2 TiO2 and 1.77 g/m2 binder.